(+)-Pilocarpine, the most important imidazole alkaloid, has been the focus of much attention for many years because of its extensive pharmacological properties. These include diaphoretic effects, stimulation of the parasympathetic system, miotic action, and particularly applications in ophthalmology. Pilocarpine is currently the drug of choice for treatment of narrow and wide angle glaucoma because it decreases the intraocular pressure and can be administered for long periods without side effects. Pilocarpine, along with its epimer isopilocarpine, was first isolated in 1875 from various species of Pilocarpus plants belonging to the Rutaceae family. The structure of this alkaloid, proposed in 1900, was later confirmed in degradation studies, X-ray analysis, and several syntheses.
Pilocarpine is a cholinergic muscarinic agonist. Although widely employed as a topical miotic for controlling the elevated intraocular pressure associated with, qlaucoma, oilocaroine has the disadvantage in having a short duration of action. The duration of intraocular pressure lowering caused by Pilocarpine lasts only for about three hours, and consequently the frequency of administration can be 3-6 times a day.